Method of making a fan

ABSTRACT

A setscrew aperture is produced on the surface of a sheet metal workpiece by deforming a portion of the workpiece surface, as by lancing and crimping or by bending a pair of spaced, aligned punched tabs, to define a setscrew passageway which may be threaded coincidentally with the deforming step or in a later step.

I Unlted States Patent [151 3,638,470

Ostrognai 1 Feb. 1, 1972 [54] METHOD OF MAKING A FAN 2,240,597 5/1941Whitefield ..29/l56.8 [72] Inventor: Allen Gilbert Ostrognai, FortWayne, Ind. 2352;; 3x33; 3 95;? [73] Assignee: General Electric CompanyPrimary Examiner-Charles W. Lanham l d: 19 [22] e June 69 AssistantExaminer-R. M. Rogers PP'- 831,072 Attorney-Allard A. Braddock, John M.Stoudt, Frank L. Neuhauser, Oscar B. Waddell, Ralph E. Krisher andJoseph B. 52 0.5. CI ..72/324, 72/379, 29/l56.8 B Fmma [51] Int. Cl...B2ld 43/28, B2lc 37/02, B2lk 3/04 581 Field of Search ..72/324, 379;10/86, 86 A, 86 B; [571 ABSTRACT 287/5208; 29/1563 A setscrew apertureis produced on the surface of a sheet metal workpiece by deforming aportion of the workpiece sur- [56] References Clted face, as by lancingand crimping or by bending a pair of UNITED STATES PATENTS spaced,aligned punched tabs, to define a setscrew passageway 138 994 5/1873 Ch29/156 8 whlch may be threaded colncldentally wlth the deformlng step8S6 or in a later te 3,006,231 10/1961 Kahn ..l0/86 p 3,072,424 1/1963Mayne ..287/52.08 X 3 Claims, 4 Drawing Figures PATENYEU E I 597? SHEET1 OF 2 sj'smo ATTORNEY ss'aaefim WWW Fm m2 SHEET 2 [1F 2 INVENTOR Alli/Va armoa/m/ ATTORNEY METHOD OF MAKING A FAN BACKGROUND OF THE INVENTIONRotatable members such as fans which are mounted on shafts are normallyfastened to the shafts either by a press fit assembly or by the use ofsetscrews. The press fit is normally reserved for those applicationswhere there is little likelihood that the rotating member will have tobe removed from the shaft after it has once been secured thereto. Whensetscrews are used the setscrew apertures are positioned in rathermassive material, such as castings, by drilling and tapping. Where therotatable member is made of sheet metal it is arranged to fit on a hubin which the setscrew aperture is drilled. This provides the strengthnecessary to enable the setscrew to be tightened sufficiently to preventrotation of the rotatable member on the shaft. The massive constructionof the member containing the setscrew aperture is costly to fabricateand, in many instances, adds also to the cost of assembling.

DESCRIPTION OF THE INVENTION The present invention is aimed at enablinga sheet metal rotatable member to be mounted directly upon a shaftinstead of a hub containing a setscrew. This is achieved by deforming aportion of the material of the rotatable member itself in order todefine a passageway in which a setscrew can be positioned.

Specific means for accomplishing the aim of the invention can best beunderstood by referring to the drawing in which FIG. 1 shows a coolingfan of the type used to cool the windings of electric motors. This fanis composed of sheet metal which has been deformed to provide twosetscrew apertures.

FIG. 2 shows the setscrew apertures from reverse side of the view shownin FIG. 1.

FIG. 3 is a sectional view of a sheet metal fan taken along the line 33of FIG. 2 showing the fan mounted on a shaft.

FIG. 4 shows an alternative embodiment of the invention wherein eachsetscrew passageway is formed from two tabs which have been punched fromthe fan material.

FIGS. 1 and 2 illustrate a fan composed of sheet metal having aplurality of spokes 11 with turned-up sides 12 constituting the bladesof the fan. A turned-up flange l3 at the center of the fan 10 serves tomount the fan on a shaft 16 (FIG. 3).

The sheet metal material of the fan 10 has been deformed in two placesto provide setscrew apertures or passageways 14 in accordance with thepreferred embodiment of this invention. The apertures 14 are formed bypunching a portion of the flange 13 to enable a setscrew 15 to protrudethrough the flange and engage the shaft 16 on which the fan 10 ismounted. The aperture or passageway 14 is formed by stamping a pair oflancings 17 after which the material is crimped to provide three crimps18, 19 and 21. The crimps l8 and 21 are oppositely directed with respectto the crimp I9 occupying the center position. In this way the crimps18, I9 and 21 define an aperture for insertion of the setscrew 15. Thisaperture is threaded as illustrated. Threading may be accomplished in aseparate step or in a step taking place at the same time as the crimpingoperation by use of a roll tap to effect both crimping and threading.

The crimp 18 is desirably formed with a diameter slightly greater thanthe setscrew 15 which it is to accommodate. This enables the crimp 18 toserve primarily as a guide thus speeding up and simplifying theinsertion of the setscrew 15.

In the embodiment illustrated in FIG. 4, the setscrew aperture isprovided by a pair of aperture tabs 22 and 23 which are produced bypunching and lancing the sheet metal of the fan 10 and then bending thetabs defined by the lancing operation in the same direction. Theapertures defined by the punching operation may be tapped to providethreads or the setscrew 15 may be a self-tapping screw which will threadthe apertures upon insertion.

It IS necessary that setscrews provlde firm engagement with theirassociated shafts and that they resist loosening over a long period oftime. The sheet metal walls of the setscrew apertures of this inventionare much thinner than the aperture walls of conventional bored andtapped setscrew apertures. While such thin wall apertures would appearto be disadvantageous, I have found that they provide design featureswhich are definitely advantageous. For instance, thin sheet metal wallsare more resilient than thick walls. Consequently, the crimps I9 and 21of FIGS. 1 and 2 may be made slightly undersize so that they are placedin hoop tension by insertion of a setscrew. The screw is then lockedfirmly in place and shows very little disposition to loosen thereafter.In the case of the embodiment of FIG. 4 the setscrew 15 may be insertedin such a way as to leave the tabs 22 and 23 under slight springtension. This tension tends to lock the screw in position against theshaft 16. In conventional setscrews it is the slight deformation of theengaged screw and aperture threads upon tightening which maintains thescrew in set position. This action is also present in the case of thesheet metal aperture of this invention.

A fan of the type illustrated in FIG. 1 was unbalanced by the additionof a 71.7 gram weight to one of the blades. After running for I year ona cycle of 4 minutes running and I minute off the setscrews still heldthe fan firmly positioned on the shaft.

While this invention has been described with reference to two specificembodiments, it is obvious that there may be additional constructions ofsheet metal setscrew apertures which fall within the proper scope ofthis invention. Accordingly, it is intended that this invention belimited in scope only as may be necessitated by the scope of theappended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A method of forming a sheet material fan for assembly with arotatable dynamoelectric machine shaft, the fan including a sheetmaterial body having a shaft accommodating opening therein, a generallyplanar section and at least two spacedapart members arranged toaccommodate a fastener and to be held in tension thereby while thefastener bears against a shaft disposed in the shaft accommodatingopening; said method comprising forming at least two spaced-apart sheetmaterial securing means in the body of the fan and establishing aperturemeans for receiving and holding a fastener in firm engagement with ashaft disposed in the shaft accommodating opening of the fan, wherebythe fan may be firmly fixed on the shaft for rotation therewith duringoperation of the dynamoelectric machine fonning at least twospaced-apart sheet material securing means in the body of the fanincludes severing a segment of the sheet material body along thegenerally planar section and deforming at least two parts of thegenerally planar section adjacent to the severed segment of the sheetmaterial body away from the sheet material body.

2. The method of claim 1 wherein forming at least two spaced-apart sheetmaterial securing means in the body of the fan further includesthreading the parts of the generally planar section adjacent to thesevered segment of the sheet material body.

3. The method of claim 1 further including the step of tapping the partsof the generally planar section adjacent to the severed segment of thesheet material body.

1. A method of forming a sheet material fan for assembly with arotatable dynamoelectric machine shaft, the fan including a sheetmaterial body having a shaft accommodating opening therein, a generallyplanar section and at least two spaced-apart members arranged toaccommodate a fastener and to be held in tension thereby while thefastener bears against a shaft disposed in the shaft accommodatingopening; said method comprising forming at least two spaced-apart sheetmaterial securing means in the body of the fan and establishing aperturemeans for receiving and holding a fastener in firm engagement with ashaft disposed in the shaft accommodating opening of the fan, wherebythe fan may be firmly fixed on the shaft for rotation therewith duringoperation of the dynamoelectric machine forming at least twospaced-apart sheet material securing means in the body of the fanincludes severing a segment of the sheet material body along thegenerally planar section and deforming at least two parts of thegenerally planar section adjacent to the severed segment of the sheetmaterial body away From the sheet material body.
 2. The method of claim1 wherein forming at least two spaced-apart sheet material securingmeans in the body of the fan further includes threading the parts of thegenerally planar section adjacent to the severed segment of the sheetmaterial body.
 3. The method of claim 1 further including the step oftapping the parts of the generally planar section adjacent to thesevered segment of the sheet material body.